Folding stool



FOLDING STOOL Filed June 27, 1961 2 Sheets-Sheet l C. A. SOANS FOLDINGSTOOL Jan. 8, 1963 2 Sheets-Sheet 2 Filed June 27,- 1961 high, betweenthe floor and the seat.

United States Patent Ofifice 3,h72,2l6 Patented Jan. 8, 1963 3,072,216FOLDHNG STQGL v Cyril Arthur Scans, flak Park, ii]. (135 S. La SalleSt., Chicago 3, I11.) Filed June 27, 1953., Ser. No. 121,296 7 flairns.35. 182-635) The invention relates to a folding stool in the form of astep-ladder for occasional use as such in a home or elsewhere, but whichis generally kept folded so that the lower step or steps are caged underthe top step or platform of the structure so that the top step. canserve as a seat. Such a structure has a self-standing main supportingbase or frame, the floor dimensions of which are desirably of relativelysmall size so that a minimum of floor area is needed for storage or whenit is used as a seat.

The usual type of step-stool, when unfolded, may have enough stabilitywhen the feet of the user are on a lower step, but when both feet are onthe top platform and maximum safety is needed, the unfolded and extendedstair part is of little or no help to the stability of the main base.Most persons standing with both feet on the top platform fail to realizethat the extended stair part does not function as a rigid frontextension or brace for the main base, and adds little to the stabilityof the structure.

Many accidents have resulted from the collapsing of stepping stools dueto reaction forces exerted backwardly by a person standing on the topplatform and facing a wall towards which the person is applying aforward pressure.

The principal object of the present invention is to provide a foldingstair structure of the class described having a foldable lower stairelement which when unfolded is so locked to the main base structure thatit serves as a rigid truss or reversed cantilever projecting from themain base.

A further object is to provide a self-locking arrangement of the classdescribed which a person can fold and unfold by simple movements of onehand only.

Another object is to provide a structure of the class described whichwhen in folded or unfolded conditions, can with one hand be picked upand set down, and carried from place to place Without requiring anyre-adjustment of its parts as a result of such activities.

Other objects, features and advantages will be described as thedescription proceeds.

In the drawings accompanying this written description the invention isshown as incorporated in a step-stool of the household type having aseat height of about 24" with a folding stair of 2 steps which are sospaced that when the stair is unfolded there are three rises, each about8" In said drawings:

FIG. 1 is a side elevation of the stool in unfolded and locked conditionwhen used as a step ladder, with certain parts broken away.

FIG. 2 is a fragmentary front elevation of the stool in the unfolded orlocked condition.

FIG. 3 is a view similar to FIG. 1, but showing the rear or inner end ofthe stair raised by the hand into unlocked condition so that it can beswung upwardly and rearward- 1y into its caged position.

FIG. 4 is a side elevation of the stool in fully folded condition withthe stair caged under the seat.

FIG. 5 is a side elevation similar to FIG. 1 with the outer end of thestair shimmed up from the floor to demonstrate the locking feature.

FIG. 6 is an enlarged fragmentary sectional plan view taken on the line7-7 of FIG. 1.

FIG. 7 is an enlarged perspective view of the linkage unit whichconstitutes a floating pivotal connection between the base structure andthe folding stair element.

Referring to the drawings, the main base frame comprises a top step orplatform It} to which are rigidly secured a pair of front legs 11 and 12and a pair of rear legs 13 and 14. To prevent racking of the frame thetop platform 10 is made with an integral depending continuous outerflange 15, and the legs are also secured together by means of a stoutintegral lower outer frame element which comprises side pieces 16 and 17and a rear crosspiece 18. The front legs 11 and 12 of the frame which inthe present instance are angular in cross-section, are secured togetherby a circular rod, the ends of which are made with open-ended verticalslots as at 19 (see FIG. 6) to receive the front flanges 21 of the frontlegs 11 and 12. The ends of the rod 19 are fastened to the webs of saidleg-flanges by means to pins or rivets 22.

The folding stair-"element comprises a pair of side plates 23 and 24 towhich are rigidly united a bottom step 25 and a middle step 26. Thisintegral stair element has 'a pair of front ends or feet 25 and .26which engage the floor a substantial distance in front of the main framewhen the stair element is unfolded or extended, as shown in FIGS. 1 and2. These feet are tied together by a crossbar 27 the ends of whichextend through and project outwardly beyond the side plates as shown inFIG. 2, said proiections 23 and .29 being flattened so that when thestair is folded and caged within the main frame, the fiattened ends willlie against the front flanges of the front legs 14 and 13 as shown inFIG. 4. In this fully folded position the ends of the cross-bar 27 serveas limit stops for preventing the stair element from dropping to thefloor when the stair is caged. l

The folding stair element is pivoted to the base structure so as toswing from its folded position outwardly about the horizontal axis ofthe stationary tie rod 1). However, the stair is also capable of movingdownwardly as a unit relative to the base so that it can be locked orrendered incapable of folding or collapsing when it is in its fullyextended condition. Said locking movement of the stair relative to thebase is preferably effected by providing an inclined link element 30 therear end of which is pivoted directly upon the base, preferably on tierod 19. The outer end of such link-element is pivoted to thestair-element, in the present instance about an axis 31 locatedpreferably above the level of the axis of the tie rod 19 (see FIGS. 1, 2and 5).

Referring to FIGS. 2 and 7, it will be seen that the link-element 30comprises a pair of side elements suit ably spaced to fit between theside plates 14- and 13, with some clearance to permit relative pivotalmovement of the link element and the stair element and thus permit alimited amount of upward movement of the stair as a unit relative to thebase-frame when the arrangement is in the extended or unfoldedcondition. The parallel links 32 nad 33 are held in rigid spacedrelation by a stout torsion tube 35 the ends of which are welded to theopposed insde faces of said links 32 and 33. The outer ends of saidlinks are apertured to pivot on the rod 36 extending through the sideplates 23 and 24 of the stair-element. One end of said rod 36 is firmlysecured against rotation in said side plate while the other end of therod 36 is threaded to loosely fit threads formed in the apertured outerend 37 of the link 32. The threaded end of rod 36 extends outwardlythrough the side plate 24 to screw into an outer locknut in the form ofa plate 38 (see FIG. 5) which plate is secured in position by a lockingscrew 39 v The stair element, as a whole, is alway'sr'naintained in acentral position relative to the legs 11 and 12 of the base by means ofa pair of spacing collars 4t) and 41 on the ends of the tie-rod 19 andlocated, as shown best in FIGS. 6 and 7, between the inside edge of thefront leg flanges 21 and the outer face of the links 32. The torsiontube 35 serves to maintain the links 32 at all times in the same plane,thereby preventing the stair-element from racking or twisting during thefolding or unfolding movement. Hence the stair-element will always swingcentrally in the frame and clashing due to careless operation will beavoided.

The stair is locked in unfolded non-collapsible condition by a pair ofinterengaging parts which are mounted respectively on the base and theupper end of the stair element preferably some distance above the mainpivot rod 19. Although under some circumstances a single pair or set oflocking parts could be used, in the present instance two sets, one ateither side of the base frame, are provided.

In each set of locking parts the part mounted on the base as best shownin FIG. 6, comprises a cam-bracket in the form of an angular platehaving a vertical mounting flange 42 which is riveted or welded to theinside face of the front leg flange 21, and an inwardly extending camflange 43 disposed in a vertical plane. The cam flange has its top edgesloping rearwardly and downwardly at an angle of about 45 to thehorizontal, and is provided with a locking slot open at its upper end asshown at 45 and extending inwardly and downwardly at an angle of about60 to the horizontal as shown at 46.

The width of the slot 46 and the opening 45 is slightly more than thediameter of the locking pin 47 carried by the stair-element. Above theopening 45 the front or outer edge of the slot 46 is extended upwardlyso as to provide an abutment 48 to limit the front movement of thecircular locking pin 47. The locking pin 47 constitutes one end of alocking rod 49 extending between the spaced sets of interengagingelements, the other end of the rod constituting a locking pin foranother similar set of parts mounted on the other front leg 12 of theframe. The locking rod 49 is rotatably mounted in holes bored in theupper ends of steel straps 50 secured to the outer faces of theside-plates 23 and 24. Excessive longitudinal sliding movement of therod 49 in the straps 50 is prevented by opposed collars 51 (see FIG. 6)fixed on the rod 49 by set screws 52. In the extended position shown inFIG. 1, the locking rod 49 preferably engages the bottom ends of thecam-slots 46v so as to limit the downward movement of the upper end ofthe stair, and in this position the oblique rear edges 53 of the stairmay also engage the spaced collars 40 and 41 on the tie rod. By thisarrangement the inner end of the inclined stair is supported by the mainframe when a person stands on the stair.

In FIG. the unfolded stool is shown with the front legs of the framespaced from the floor by means of shims or blocks 54 placed under thesoles of the front feet 25 and 26 of the stair. This drawing is intendedto illustrate the manner in which the locking means prevents collapsingof the stool when a person stands on the top step facing the rear andengages in some activity which results in the application of a forcewhich tends to rock the base frame forwardly around a horizontal axisextending through the two front feet 55 of the base. From an examinationof this FIG. 5 drawing it will be observed that the relation between theposition and inclination of the cam-slot 46, the position of main pivot19 and the position and length of the link element 30, and the stairpivot 36, is such that in the unfolded position the stair, so far asresistance to forces tending to fold the stair is concerned, is rendereduncollapsible and functions in effect as a reversed cantilever extendingforwardly from and forming a rigid forward extension of, the base frame.

FIG. 3 shows the position of the stair and the locking parts when theoperator is beginning the folding operation. To fold the stair, theoperator places his hand or fingers under the middle step 26 and liftsup the stair so as to slide the lock pins 47 upwardly and forwardlyuntil they are raised out of the cam-slots 46. Without further ado thestair assembly can then be swung rearwardly around the axis of thetie-rod 19 until it reaches the fully folded or upside-down positionshown in FIG. 4. Excessive upward movement of the upper end of the stairas an incident to the unlocking step of the folding movement isundesirable because of space limitations and the normal clearancesrequired in a folding structure of the type described. Hence, the bodilyupward movement of the stair is limited by a small cross rod 56extending through and between the side plates 23 and 24 of the stair andpositioned to engage the bottom edges of the links 32 and 33 when thestair has reached the top limit of its upward unlocking movement. Tounfold the stool the cross bar 27 (see FIG. 4) is pulled forwardly byone hand and the stair is thus rocked outwardly until the locking pins47 engage the cam 44, and are thus cammed up far enough to drop into theslots 46.

In the unfolded position the entire stool can be lifted from the floorby one hand placed under the front edge of the top platform 10 and movedfrom place to place without danger of dislocating the lockingarrangement.

A patent is solicited for any and all herein disclosed patentablesubject matter invented by applicant.

The embodiment disclosed herein may be changed or modified withoutdeparting from the scope of the invention.

Subject matter now believed to be patentable and invented by applicantis set forth in the appended claims.

I claim:

1. A portable folding step ladder which has A. a floor-supported rigidcage-like self-standing basestructure having a top platform.

B. a stair normally caged and folded within said basestructure andadapted to be unfolded by an outward and downward swinging movement fromits caged position to its extended position so as to engage the floor toprovide a step which (X) is at a height intermediate the floor and theplatform and (Y) projects outwardly from the base-structure, and

C. a set of two inter-engageable parts which are carried respectively bythe base and the stair and which in the extended position are adapted toengage each other to form a lock for preventing forward tilting movementof the base.

D. said inter-engageable parts being adapted to be disengaged by alimited upward movement of the stair relative to the base-structure soas to allow the stair to be folded and thereby caged Within thebasestructure.

2. A portable folding stool which has A. a rigid self-standing baseframe having floor engaging legs at its front and back,

B. a platform supported by said legs and adapted to serve as a seat or atop step.

C. an extendable stair provided with a lower step and an upper step,

D. a pivotal connection between the frame and the stair permitting, inthe extended position of the stair, a limited amount of up and downbodily movement of the stair and also thereafter permitting a rearwardlyswinging movement of the stair relative to the base between the extendedposition and a reversed upsidedown caged position under the platform,

B. said swinging movement being around an axis located intermediate theupper step and the floor and adjacent the front of the frame, and

F. a set of two inter-engaging locking parts mounted respectively on thebase and on the stair, and which in the extended position, when engaged,prevent said swinging movement, and which, in the extended positionprevent forward tilting movement of the base, but are capable of beingengaged or disengaged by said bodily movement of the stair relative tothe base so as to prevent or permit said swinging movement.

3. The combination of claim 2 in which the interengaging part on thebase is located intermediate the platform and the swinging axis of thestair.

4. The combination of claim 2 in which the pivotal connection comprisesa link one end of which is pivotally connected to the base so as topermit said swinging movement and the other end of which is pivotallyconnected to the stair so as to permit said limited up and downmovement.

5. The combination of claim 2 in which the pivotal connection comprisesa pair of horizontally spaced links each of which has one end pivotallyconnected to the base so as to permit said swinging movement and has itsother end pivotally connected to the stair so as to permit said limitedup and down movement, means being provided for compelling said links toswing in unison with each other.

6. The combination of claim 1 in which the interengaging part which ison the base is located at a distance above the axis of said swingingmovement, and which combination includes cam means for automaticallyeffecting said engagement as an incident to the unfolding swingingmovement of the stair.

7. A portable folding step ladder which has A. a floor-supported rigidcage-like self-standing base structure having a top platform. B. a stairnormally caged and folded within said base structure and adapted to beunfolded by an outward movement from its caged position to its extendedposition so as to engage the floor outside the base area and to providea step which (X) is at a height intermediate the floor and the platformand (Y) projects outwardly from the base structure.

C. a set of two inter-engageable parts which are carried respectively bythe base and the stair and which, in the extended position, are adaptedto engage each other to form a lock for preventing folding movement ofthe stair.

D. said inter-engageable parts being adapted to be disengaged by alimited upward movement of the stair relative to the base-structure soas to release said lock and allow the stair to be folded and therebycaged within the base structure.

B. one of said inter-engageable parts including a cam co-operating withthe other inter-engageable part for automatically effecting saidengagement as an incident to the outward movement of the stair.

References Iited in the file of this patent UNITED STATES PATENTSFOREIGN PATENTS Great Britain Mar. 30, 1955

7. A PORTABLE FOLDING STEP LADDER WHICH HAS A. A FLOOR-SUPPORTED RIGIDCAGE-LIKE SELF-STANDING BASE STRUCTURE HAVING A TOP PLATFORM. B. A STAIRNORMALLY CAGED AND FOLDED WITHIN SAID BASE STRUCTURE AND ADAPTED TO BEUNFOLDED BY AN OUTWARD MOVEMENT FROM ITS CAGED POSITION TO ITS EXTENDEDPOSITION SO AS TO ENGAGE THE FLOOR OUTSIDE THE BASE AREA AND TO PROVIDEA STEP WHICH (X) IS AT A HEIGHT INTERMEDIATE THE FLOOR AND THE PLATFORMAND (Y) PROJECTS OUTWARDLY FROM THE BASE STRUCTURE. C. A SET OF TWOINTER-ENGAGEABLE PARTS WHICH ARE CARRIED RESPECTIVELY BY THE BASE ANDTHE STAIR AND WHICH, IN THE EXTENDED POSITION, ARE ADAPTED TO ENGAGEEACH OTHER TO FORM A LOCK FOR PREVENTING FOLDING MOVEMENT OF THE STAIR.D. SAID INTER-ENGAGEABLE PARTS BEING ADAPTED TO BE DISENGAGED BY ALIMITED UPWARD MOVEMENT OF THE STAIR RELATIVE TO THE BASE-STRUCTURE SOAS TO RELEASE SAID LOCK AND ALLOW THE STAIR TO BE FOLDED AND THEREBYCAGED WITHIN THE BASE STRUCTURE. E. ONE OF SAID INTER-ENGAGEABLE PARTSINCLUDING A CAM CO-OPERATING WITH THE OTHER INTER-ENGAGEABLE PART FORAUTOMATICALLY EFFECTING SAID ENGAGEMENT AS AN INCIDENT TO THE OUTWARDMOVEMENT OF THE STAIR.